Dray A, Bettaney J, Forster P
Sandoz Institute for Medical Research, London, U.K.
Neurosci Lett. 1989 Apr 24;99(1-2):50-4. doi: 10.1016/0304-3940(89)90263-2.
Capsaicin was tested on peripheral fibres in vitro to determine whether evoked depolarization or desensitization were likely to explain the antinociception observed after acute systemic capsaicin in vivo. The activation of peripheral fibres by noxious (capsaicin, bradykinin, heat) and innocuous (light brush) stimuli was recorded as a depolarization of a spinal ventral root (L3-L5) in the neonatal rat spinal cord with attached tail. Prolonged superfusion of the tail with low doses (0.2-2 microM) of capsaicin produced a short lasting depolarization followed by a complete loss of sensitivity to capsaicin without changes in sensitivity to other noxious or innocuous stimuli. Partial recovery from this selective desensitization could be observed 3-5 h later. In most preparations superfusion of the tail with 20 microM capsaicin produced a prolonged and non-selective impairment of sensitivity to all noxious stimuli. These data suggest that neither depolarization by capsaicin nor the selective desensitization of peripheral fibres to capsaicin are likely to account for the acute antinociceptive effect of systemic capsaicin. On the other hand the non-selective reduction in sensitivity to noxious stimuli induced by capsaicin may contribute to its antinociceptive action.
在体外对辣椒素作用于外周纤维进行了测试，以确定诱发的去极化或脱敏是否可能解释急性全身应用辣椒素后在体内观察到的抗伤害感受。用有害（辣椒素、缓激肽、热）和无害（轻刷）刺激激活外周纤维，记录为新生大鼠脊髓（连尾）L3-L5脊髓腹根的去极化。用低剂量（0.2-2微摩尔）辣椒素长时间灌注尾巴，会产生短暂的去极化，随后对辣椒素完全失去敏感性，而对其他有害或无害刺激的敏感性没有变化。3-5小时后可观察到这种选择性脱敏的部分恢复。在大多数制剂中，用20微摩尔辣椒素灌注尾巴会对所有有害刺激产生长时间且非选择性的敏感性损害。这些数据表明，辣椒素引起的去极化以及外周纤维对辣椒素的选择性脱敏都不太可能解释全身应用辣椒素的急性抗伤害感受作用。另一方面，辣椒素引起的对有害刺激敏感性的非选择性降低可能有助于其抗伤害感受作用。
